Driving means for circuit breakers



Dec. 20, 1960 K. KRIECHBAUM 2,965,072 DRIVING MEANS FOR CIRCUIT BREAKERS Filed June 2, 1958 c'OMPREssEa Fl ll 9 l .i 1/ 7T m I I5 I A I 8 '14 I2 con/m0;

VALVES 7 .fweman' KARL mama/541m B) J, ozzlmiiz fiffbw zin A 7T ORNE V 5 DG MEANS FOR CHZCUIT'BREAKE Kari Kriechbaum, Kassel, Germany, assignor toiLicentia Patent-Verwaltungs-G.m.b,H., Hamburg, Germany Filed June 2, 1958, Set. N0.,739,288.

Claims priority, application Germany June 3, 1957 Claims. (Cl. 121-38) The present invention relates to circuit breakers, and more in particular to driving means for high-speed electric circuit breakers.

It is known in the art to provide pneumatic driving means for operating circuit breakers. As the switching operations have to be performed in a very quick succession it has already been proposed to. vent the driving means still filled with compressed air needed for the preceding switching operation. This venting is done at the beginning of the next following switching by means of the compressed air needed for this-following switching which opens one or several'venting valves. These known devices can accelerate the succession of switching operations but they are rather complicated and require expensive control means. i

It is an object of the present invention to provide driving means for operating electric circuit breakers. with which the switching speed can be greatly increased and is much greater than in known devices.

It is another object of the present invention to provide driving means for operating electric, circuit breakers, with which the switchingoperation is greatly accelerated, and which have a comparatively simple and inexpensive construction.

These objects as well as further objectsv and advantages of the present invention which will. become apparent as the description thereof proceeds. are achieved; by the driving means of the present invention comprisingcylinder and piston means efiecting the switching of: the circuit breaker, venting means, and control. means for the venting means adapted to so effect the venting of the cylinder that the latter is closed during the major portion of the switching motion of the driving pistonYbut is vented at the end or shortly before the end of the switching motion of the piston. The venting device can be controlled by pneumatic: means as well as mechanically.

According to one embodiment of the invention envis aging a mechanical control of'the venting of the. cylinder there is provided a slide valve closing in its resting position a venting passage; the slide is removed and the venting passage is opened by the driving piston as soon as the same reaches a predetermined position towards the end of the switching motion.

According to another, preferred embodiment of the present invention, the control of the venting device is efiected pneumatically by means of a venting valve comprising cylinder and piston means, means tending to open the venting valve and means foreflfecting a. balancing of pressures in the two cylinder spaces separated by the piston of the venting valve. The pressure balancing takes place towards the end of the switching motion of the driving piston and results in the opening of the venting valve.

The invention will he more fully appreciated upon the following description of the accompanying drawings wherein 2,965,072 Patented Dec. 20, 1960 Figure 1 is a sectional view of the pneumatic drive for circuit breakers of the present invention;

Figure 2 is a sectional view of a portion of another embodiment of the present invention with a mechanically operated air vent;

Figure 3 is a sectional view of a portion of the embodiment shown in Figure l with a modification in the air vent;

Figure 4 is a sectional view of a portion of the embodiment shown in Figure 1 and showing a resilient piston construction.

Figure 1 shows the driving cylinder 1 with a driving piston 2 having a tripping pin 3. The cylinder has an air inlet passage 4 for receiving a pressure medium, such as compressed air used for the circuit breaking motion, and another inlet passage 5 for receiving compressed air used for the circuit making motion. Furthermore, there is provided a centrally disposed valve 6 resting with one end in the cavity 6a of the cylinder 1, guided through the internal wall portion 6b and resting with the other end against flanges 1a and 1b of the cylinder 1. In the absence of a pressure medium or up to a predetermined pressure the valve 6 is maintained in its closed position by the pretensioned spring 7 provided in the cavity 6a. The valve 6 simultaneously serves as a guide for the tripping pin 3. At its opposite end, the cylinder 1 bears an air vent it which can be closed by the valve 9 housing a piston 10- influenced by a pressure spring 14, and a slide 11 connected to the piston 10 by a connecting rod 15. The valve 9 is equipped with pressure balancing means such as small borings 12 in the valve piston 10 or transfer passages 12a (Fig. 3).

This pneumatic drive operates in the following manner:

Compressed air intended to effect the breaking of the circuit is admitted into the inlet passage 4 and opens the valve 6. The compressed air then enters into the cylinder space housing the piston 2 and moves the latter with the tripping pin 3 into the circuit-breaking position. As soon as the piston 2 passes the opening 8, the pressure medium, e.g. the air within the cylinder space, passes to the outside. For a circuit-making. immediately following the circuit-breaking, compressed. air is admitted into the inlet passage 5 and into the valve 9 as shown by the arrows 5a and 5b. The piston 2 is pushed backward intothecircuit-making position and the valve 9 is closed as the air pushes the piston 12 with the slide 11 closing the inlet passage 8, so that the air introduced through the passage 5 cannot leave the cylinder space via the passage 8. By the time the piston 2 with the tripping pin 3 have reached the circuit-making position the air introduced into the valve as shown by the arrow 5b passes through the bore 12 (Fig. 1) in the piston 10 or through the transfer passages 12a (Fig. 3), to the other side of piston 10 so as to effect a balance of pressures in the two spacesof valve 9 separated by. the piston 10. Due to this balance of pressures and under the infiuence of spring 14 the piston 10 and the slide 11 are moved in the direction contrary to the arrow 5b. Consequently, the cylinder space within cylinder 1 i vented, thereby making possible another circuit-breaking operation immediately after the circuit-making established by the position of piston 2 and tripping pin 3.

The resetting of the slide and piston 10, 11, can also be eifected by differential piston means rather than by the spring 14.

The cylinder 1 may also have two valves, one being provided for the circuit-making air and the other being provided for the circuit-breaking air. An excessive recession of the driving piston can be prevented by providing a second venting valve and the driving piston 2 can be resiliently constructed in itself (Fig. 4).

According to another embodiment of the present in- 3 vention the venting means are mechanically operated. The slide valve 13 having a flange 13a projecting into the cylinder space enclosed by cylinder 1 is actuated by a pressure spring 18 and normally maintained in the position shown in Figure 2, closing the air vent passage 8. During the circuit-breaking motion of the piston 2 the slide 13 with its flange 13a is pushed against the infiuence of spring 18 by the upper portion of piston 2, and moves along the guide recess 19 in the upper wall of cylinder 1. Thereby the air vent passage 8 is opened and the air within the cylinder 1 is released.

While according to the invention, the venting of the driving cylinder is effected and controlled with comparatively inexpensive means of an uncomplicated construction the switching speed is drastically accelerated. Contrary to the known devices where the venting is done only at the beginning of the next following switching operation, the present invention makes it possible to effect this venting at the end or even shortly before the end of the switching motion proper for which the pressure medium was used. Immediately after the end of one switching operation it is therefore possible to effect another switching operation. The drive means of the present invention are thus capable of effecting an unprecedented high-speed switching operation and to perform a far greater number of switching operations in a given period than any of the known devices.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications Within this invention as may fall within the scope of the appended claims.

What is claimed is:

1. Driving means for high-speed electric circuit breakers comprising a driving cylinder, a driving piston, a pressure medium reciprocating said piston in said cylinder, and a tripping pin mounted on said driving piston and moving therewith, thereby effecting the switching of said circuit breaker, a venting passage communicating with said driving cylinder, and a venting valve comprising a cylinder, a piston and a slide connected to said piston and moving therewith, thereby alternatingly closing and opening said venting passage, and control means causing said slide to close said venting passage at the beginning of a switching stroke of said piston and opening said venting passage towards the end of the same switching stroke.

2. Driving means for high-speed electric circuit breakers comprising a driving cylinder, a driving piston, a pressure medium reciprocating said piston in said cylinder, and a tripping pin mounted on said driving piston and moving therewith, thereby effecting the switching of said circuit breaker, a venting passage communicating with said driving cylinder, and a venting valve com prising a cylinder, a piston and a slide connected to said piston and moving therewith, thereby alternatingly closing and opening said venting passage, with said pressure medium moving said piston and slide into closed position of said venting passage at the beginning a switching stroke of said driving piston, a plurality of borings in said piston in said venting valve allowing for the establishment of a pressure balance in said cylinder of said venting valve on either side of said piston substantially at the end of the same switching stroke of said driving piston, and means urging said piston and slide of said venting valve into opened position of said 55 venting passage and adapted to move said piston and slide into opened position during the pressure balance in said cylinder of said venting valve.

3. Driving means for high-speed electric circuit breakers comprising a driving cylinder, a driving piston, a pressure medium reciprocating said piston in said cylinder, and a tripping pin mounted on said driving piston and moving therewith, thereby effecting the switching of said circuit breaker, a venting passage communicating with said driving cylinder, and a venting valve comprising a cylinder, a piston and a slide connected to said piston and moving therewith, thereby alternatingly closing and opening said venting passage, with said pressure medium moving said piston and slide into closed position of said venting passage at the beginning a switching stroke of said driving piston, a plurality of transfer passages in said cylinder in said venting valve allowing for the establishment of a pressure balance in said cylinder of said venting valve on either side of said piston substantially at the end of the same switching stroke of said driving piston, and means urging said piston and slide of said venting valve into opened position of said venting passage and adapted to move said piston and slide into opened position during the pressure balance in said cylinder of said venting valve.

4. Driving means for high-speed electric circuit breakers comprising a driving cylinder, 3. driving piston, a pres sure medium reciprocating said piston in said cylinder, and a tripping pin mounted on said driving piston and moving therewith, thereby effecting the switching of said circuit breaker, a venting passage communicating with said driving cylinder, a pressure medium-inlet passage communicating with said driving cylinder, valve means adapted to close said driving cylinder with respect to said inlet passage and resilient means moving said valve means into closed position at a predetermined pressure difference between said driving cylinder and said inlet passage, and a venting valve comprising a cylinder, a piston and a slide connected to said piston and moving therewith, thereby alternatingly closing and opening said venting passage, and control means causing said slide to close said venting passage at the beginning of a switching stroke of said piston and opening said venting passagetowards the end of the same switching stroke.

5. Driving means for high-speed electric circuit breakers comprising a driving cylinder, a driving piston, a pressure medium reciprocating said piston in said cylinder, and a tripping pin mounted on said driving piston and moving therewith, thereby effecting the switching of said circuit breaker, a venting passage communicating with said driving cylinder, a pressure medium-inlet passage communicating with said driving cylinder, combined valve and guide means guiding said tripping pin and adapted to close said driving cylinder with respect to said inlet passage and resilient means moving said valve means into closed position at a predetermined pressure difference between said driving cylinder and said inlet passage, and a venting valve comprising a cylinder, a piston and a slide connected to said piston and moving therewith, thereby alternatingly closing and opening said venting passage, and control means causing said slide to close said venting passage at the beginning of a switching stroke of said piston and opening said venting passage towards the end of the same switching stroke.

References Cited in the file of this patent UNITED STATES PATENTS 2,467,434 Kupiec Apr. 19, 1949 2,740,859 Beatty H--. Apr. 3, 1956 2,769,912 Lupfer Nov. 6, 1956 

